Supergirl aimed for a strong mid-season finale with both a (temporary) fix to the Cadmus arc. More noticeably however, it aimed to start the long-anticipated “Invasion!” CW crossover. Supergirl “Medusa”: Thanksgiving With Supergirl The episode opens up with a Thanksgiving meal between Kara (Melissa Benoit), her mother Eliza (Helen Slater), Alex (Chyler Leigh), Winn (Jeremy Jordan), Mon-El (Chris Wood), and …